1. Field of the Invention
The present invention relates to an electric motor, which includes brushes that slidably contact a commutator.
2. Description of Related Art
In one type of previously known electric motor, brushes slidably contact a commutator, which is fixed to a rotatable shaft to rotate integrally therewith. Electric power is supplied to the commutator through the brushes.
Japanese Unexamined Patent Publication No. 2003-523708A (corresponding to US 2002/0149283A1) discloses one such motor. In this motor, a commutator is placed axially outward of a yoke housing, which is configured into a cup shaped body. Brushes, which slidably contact the commutator, are held by a brush holder at outside of the yoke housing. Furthermore, in this motor, an electronic control unit (ECU) is placed in parallel with the commutator and the brush holder at a location, which is on one axial side of the yoke housing in the direction of the axis of the rotatable shaft that projects from the yoke housing. In this way, the axial length of the yoke housing is made shorter than the yoke housing of the other type of motor, which receives the commutator and the brush holder in the yoke housing.
In the case of the motor of Japanese Unexamined Patent Publication No. 2003-523708A (corresponding to US 2002/0149283A1), at the time of installing the brushes to the brush holder, the installation locations of the brushes on the brush holder are located outside of the yoke housing, i.e., are located at the gear housing side, and thereby the brushes are installed to the brush holder from the gear housing side. Because of this construction, after the installation of the yoke housing and the brush holder, the entire assembly, to which the yoke housing and the brush holder are installed, needs to be inverted such that the yoke housing bottom side is placed at the lower side of the assembly, and the brush holder side is placed at the upper side of the assembly. Thereafter, the brushes are installed to the brush holder, which is now placed at the upper side of the assembly. This results in the tedious assembling process.
In contrast, in the case of the motor, in which the brush holder is entirely received in the yoke housing, the brushes can be installed to the brush holder from the yoke housing side. Therefore, it is not required to invert the brush holder. However, in the case of this type of motor, the brush holder is entirely received in the yoke housing. Thereby, the entire axial length of the yoke housing is disadvantageously lengthened. Thus, it has been demanded to address such a disadvantage.